Re: TLB and PTE coherency during munmap

[Catalin Marinas <catalin.marinas@arm.com>]

On 29 May 2013 18:51, Peter Zijlstra <peterz@infradead.org> wrote:
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -384,6 +384,21 @@ void tlb_remove_table(struct mmu_gather *tlb, void *table)
>
>  #endif /* CONFIG_HAVE_RCU_TABLE_FREE */
>
> +static inline void cond_resched_tlb(struct mmu_gather *tlb)
> +{
> +#ifndef CONFIG_PREEMPT
> +       /*
> +        * For full preempt kernels we must do regular batching like
> +        * SMP, see tlb_fast_mode(). For !PREEMPT we can 'cheat' and
> +        * do a flush before our voluntary 'yield'.
> +        */
> +       if (need_resched()) {
> +               tlb_flush_mmu(tlb);
> +               cond_resched();
> +       }
> +#endif
> +}

Does it matter that in the CONFIG_PREEMPT case, you no longer call
cond_resched()? I guess we can just rely on the kernel full preemption
to reschedule as needed.

--
Catalin

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